Donna M. Bayliss

Mapping the Developmental Constraints on Working Memory Span Performance.

This study investigated the constraints underlying developmental improvements in complex working memory span performance among 120 children of between 6 and 10 years of age. Independent measures of processing efficiency, storage capacity, rehearsal speed, and basic speed of processing were assessed to determine their contribution to age-related variance in complex span. Results showed that developmental improvements in complex span were driven by 2 age-related but separable factors: 1 associated with general speed of processing and 1 associated with storage ability. In addition, there was an age-related contribution shared between working memory, processing speed, and storage ability that was important for higher level cognition. These results pose a challenge for models of complex span performance that emphasize the importance of processing speed alone.

Effect of age on dual-task performance in children and adults

Age effects on dual-task costs were examined in healthy adults (Exp. 1) and in typically developing children (Exp. 2). In both experiments, individual differences in performance on the single-task components were titrated so that any age differences in dual-task costs could not be attributed to differences in single-task performance. Dual-task costs were found, but there were no age-related differences in these costs in older relative to younger adults, in 7-year-old relative to 9-year-old children, or across all four age groups. The results from these experiments suggest that previously reported age differences in dual-task costs, in both healthy ageing and child development, may be due to a failure to adequately equate single-task difficulty.

Chronic Illness and Developmental Vulnerability at School Entry

OBJECTIVE: This study examined the association between chronic illness and school readiness, by using linked administrative population data. METHODS: The sample included children born in 2003–2004 who were residing in Western Australia in 2009 and had a complete Australian Early Development Census record (N = 22 890). Health and demographic information was also analyzed for 19 227 mothers and 19 030 fathers. The impact of child chronic illness on 5 developmental domains (social, emotional, language, cognitive, and physical) at school entry was analyzed. Analyses examined the association between child developmental outcomes and chronic illness generally, single or multiple chronic illness diagnosis, and diagnosis type. Logistic regression models estimated odds ratios for each outcome, adjusted for child, parent, and community sociodemographic variables. RESULTS: In the adjusted models, children with a chronic illness had an increased risk of being classified as developmentally vulnerable on all domains, compared with children without a chronic illness (20%–35% increase in risk). There was no increased risk for children with multiple chronic illness diagnoses over those with a single diagnosis (all Ps > .05). There was no evidence of a disease-specific effect driving this risk. CONCLUSIONS: Regardless of the number or type of conditions, chronic illness in young children is a risk factor for reduced school readiness. These effects were seen for health conditions not traditionally considered detrimental to school readiness, such as chronic otitis media. Thus, the implications of a broader range of chronic health conditions in early childhood on school readiness need to be considered.

Are the Autism and Positive Schizotypy Spectra Diametrically Opposed in Empathizing and Systemizing

Crespi and Badcock’s (Behaviour Brain Sci 31: 241–261, 2008) novel theory, which presents autism and positive schizophrenia as diametrical opposites on a cognitive continuum, has received mixed support in the literature to date. The current study aimed to further assess the validity of this theory by investigating predictions in relation to empathizing and systemizing. Specifically, it is predicted by Crespi and Badcock that while mild autistic traits should be associated with a cognitive profile of superior mechanistic cognition (which overlaps with systemizing) but reduced mentalistic cognition (which overlaps with empathizing), positive schizotypy traits should be associated with the opposite profile of superior mentalistic but reduced mechanistic cognition. These predictions were tested in a student sample using a battery of self-report and behavioural measures. The pattern of results obtained provides no support for Crespi and Badcock’s theory.

Poorer divided attention in children born very preterm can be explained by difficulty with each component task, not the executive requirement to dual-task

ABSTRACT Children born very preterm (VP, ≤ 32 weeks) exhibit poor performance on tasks of executive functioning. However, it is largely unknown whether this reflects the cumulative impact of non-executive deficits or a separable impairment in executive-level abilities. A dual-task paradigm was used in the current study to differentiate the executive processes involved in performing two simple attention tasks simultaneously. The executive-level contribution to performance was indexed by the within-subject cost incurred to single-task performance under dual-task conditions, termed dual-task cost. The participants included 77 VP children (mean age: 7.17 years) and 74 peer controls (mean age: 7.16 years) who completed Sky Search (selective attention), Score (sustained attention) and Sky Search DT (divided attention) from the Test of Everyday Attention for Children. The divided-attention task requires the simultaneous performance of the selective- and sustained-attention tasks. The VP group exhibited poorer performance on the selective- and divided-attention tasks, and showed a strong trend toward poorer performance on the sustained-attention task. However, there were no significant group differences in dual-task cost. These results suggest a cumulative impact of vulnerable lower-level cognitive processes on dual-tasking or divided attention in VP children, and fail to support the hypothesis that VP children show a separable impairment in executive-level abilities.

Poor executive functioning in children born very preterm: Using dual-task methodology to untangle alternative theoretical interpretations

Two alternative theoretical explanations have been proposed for the difficulties with executive functioning observed in children born very preterm (VP; ⩽32 weeks): a general vulnerability (i.e., in attentional and processing capacities), which has a cascading impact on increasingly complex cognitive functions, and a selective vulnerability in executive-level cognitive processes. It is difficult to tease apart this important theoretical distinction because executive functioning tasks are, by default, complex tasks. In the current study, an experimental dual-task design was employed to control for differences in task difficulty in order to isolate executive control. Participants included 50 VP children (mean age=7.29 years) and 39 term peer controls (mean age=7.28 years). The VP group exhibited a greater dual-task cost relative to controls despite experimental control for individual differences in baseline ability on the component single tasks. This group difference also remained under a condition of reduced task difficulty. These results suggest a selective vulnerability in executive-level processes that can be separated from any general vulnerability.

How quickly they forget: The relationship between forgetting and working memory performance

This study examined the contribution of individual differences in rate of forgetting to variation in working memory performance in children. One hundred and twelve children (mean age 9 years 4 months) completed 2 tasks designed to measure forgetting, as well as measures of working memory, processing efficiency, and short-term storage ability. Individual differences in forgetting rate accounted for unique variance in working memory performance over and above variance explained by measures of processing efficiency and storage ability. In addition, the nature of the variation in forgetting was more consistent with a nonexecutive forgetting parameter than an executive ability associated with resistance to interference. These findings indicate that individual differences in the rate at which information is lost from memory is an important constraint on childrens working memory performance, which has implications for current models of working memory that do not incorporate such a factor.

The relationship between sleep and working memory in children with neurological conditions

ABSTRACT The objective of this study is to investigate whether sleep problems might account for the increased working memory deficits observed in school-aged children with neurological conditions. A novel, transdiagnostic approach to the investigation was chosen, and sleep is treated as a process that can potentially account for working memory difficulties across a range of neurological conditions. Prevalence estimates of sleep problems are also examined. Archival data of 237 children aged 6 to 11 years were collected from a Western Australian statewide neuropsychological service for the period 26 July 2011 to 14 January 2014. Measures of parent-reported sleep quality, snoring, and daytime sleepiness were obtained, in addition to objective measures of verbal and spatial working memory, storage capacity, and processing speed. The results of the data analysis reveal that over one third of participants reported having clinically-significant levels of sleep problems and that poor sleep quality is significantly associated with verbal working memory difficulties. This association remains after partialling out the variance contributed to performance by storage capacity and processing speed, suggesting that sleep is impacting upon an executive component of working memory. No other significant associations are observed. The results suggest that poor sleep quality is associated with an executive component of verbal (rather than spatial) working memory in children with neurological conditions. This has implications for the biological mechanisms thought to underlie the relationship between sleep and cognition in children. The results also demonstrate the clinical utility of a transdiagnostic approach when investigating sleep and cognition in children with neurological conditions.

The relationship between sleep problems and working memory in children born very preterm

ABSTRACT In two studies, the relationship between sleep and working memory performance was investigated in children born very preterm (i.e., gestation less than 32 weeks) and the possible mechanisms underlying this relationship. In Study 1, parent-reported measures of snoring, night-time sleep quality, and daytime sleepiness were collected on 89 children born very preterm aged 6 to 7 years. The children completed a verbal working memory task, as well as measures of processing speed and verbal storage capacity. Night-time sleep quality was found to be associated with verbal working memory performance over and above the variance associated with individual differences in processing speed and storage capacity, suggesting that poor sleep may have an impact on the executive component of working memory. Snoring and daytime sleepiness were not found to be associated with working memory performance. Study 2 introduced a direct measure of executive functioning and examined whether sleep problems would differentially impact the executive functioning of children born very preterm relative to children born to term. Parent-reported sleep problems were collected on 43 children born very preterm and 48 children born to term (aged 6 to 9 years). Problematic sleep was found to adversely impact executive functioning in the very preterm group, while no effect of sleep was found in the control group. These findings implicate executive dysfunction as a possible mechanism by which problematic sleep adversely impacts upon cognition in children born very preterm, and suggest that sleep problems can increase the cognitive vulnerability already experienced by many of these children.

School readiness of maltreated children: Associations of timing, type, and chronicity of maltreatment

Children who have been maltreated during early childhood may experience a difficult transition into fulltime schooling, due to maladaptive development of the skills and abilities that are important for positive school adaptation. An understanding of how different dimensions of maltreatment relate to childrens school readiness is important for informing appropriate supports for maltreated children. In this study, the Australian Early Development Census scores of 19,203 children were linked to information on child maltreatment allegations (substantiated and unsubstantiated), including the type of alleged maltreatment, the timing of the allegation (infancy-toddlerhood or preschool), and the total number of allegations (chronicity). Children with a maltreatment allegation had increased odds of poor school readiness in cognitive and non-cognitive domains. Substantiated maltreatment was associated with poor social and emotional development in children, regardless of maltreatment type, timing, or chronicity. For children with unsubstantiated maltreatment allegations, developmental outcomes according to the type of alleged maltreatment were more heterogeneous; however, these children were also at risk of poor school readiness irrespective of the timing and/or chronicity of the alleged maltreatment. The findings suggest that all children with maltreatment allegations are at risk for poor school readiness; hence, these children may need additional support to increase the chance of a successful school transition. Interventions should commence prior to the start of school to mitigate early developmental difficulties that children with a history of maltreatment allegations may be experiencing, with the aim of reducing the incidence of continuing difficulties in the first year of school and beyond.